Table 1. Use of sensory inputs for balance control (Adopted from Nashner, 1997).

Sensory input	Reference	Conditions  favorable to use	Conditions  unfavorable to use
Somatosensory	Support surface	Fixed support surface	Irregular or moving support surface
Visual	Surrounding  objects	Fixed visible surroundings Irregular or moving support surface	Moving  surroundings Darkness
Vestibular	Gravity Inertial space	Irregular or moving support surface Moving surroundings Darkness	Unusual motion environments